Knowing the historical context of Christopher Marlowe's Doctor Faustus helps us better understand the plot and characters of the play, as well as its deeper meanings and message. Let's see how this works.
The protagonist, Faustus, is a scholar. He embodies many of the traits of the Renaissance, including the drive for knowledge, the emphasis on the individual, the appreciation of the classics, and a “this worldly” focus. He also becomes the vehicle for Marlowe's critique of these characteristics when they go beyond the bounds of moderation.
Faustus longs for knowledge. When he has exhausted all the normal means of attaining it, he is still not satisfied, and he turns to supernatural means, means that are forbidden because they are spiritually deadly. Faustus knows this, but he usually doesn't care all that much. He wants to pursue his goals at all costs. He believes that his individual accomplishments are more important than anything else. He wants power and wealth and fame. Notice how his focus quickly moves beyond knowledge. Herein lies the critique. When people reach beyond themselves and the limits set for them, they fall.
Further, Marlowe nods toward the Renaissance appreciation for the classics by including figures like Alexander the Great and Helen of Troy. Faustus conjures their spirits (or an imitation of their spirits) with the help of the demon. Yet by this point, Faustus's goal is not really knowledge of them. It is to impress others and earn honor for himself. His focus is completely on the things of this world, even as he uses supernatural means to attain them.
We can see, then, that Marlowe is offering a strong critique of Renaissance interests and ideas that are misused and wrongly pursued. He is cautioning his audience to remain within the bounds of reason and morality and showing what happens when they do not.